Auto injector with detection of used cartridge and associated method

ABSTRACT

Disclosed is an auto-injector for administering a medicament, comprising: a housing; a cartridge receiver configured to receive a cartridge comprising a first stopper; a drive module coupled to move a plunger rod configured to move the first stopper; a resistance sensor configured to provide a resistance signal indicative of resistance against movement of the plunger rod; and a processing unit coupled to the drive module and to the resistance sensor. The processing unit being configured to: control the drive module to move the plunger rod towards the extended plunger rod position; determine present plunger rod position; receive the resistance signal; determine a cartridge parameter based on the resistance signal and the present plunger rod position; and control the drive module to adjust the movement of the plunger rod based on the cartridge parameter.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase Application of PCTInternational Application Number PCT/EP2016/082860, filed on Dec. 29,2016, designating the United States of America and published in theEnglish language, which is an International Application of and claimsthe benefit of priority to European Patent Application No. 15203172.0,filed on Dec. 30, 2015. The disclosures of the above-referencedapplications are hereby expressly incorporated by reference in theirentireties.

The present disclosure relates to an auto injector, such as anelectronic auto injector, a system comprising an auto injector and acartridge, and a method for operating an auto injector.

INTRODUCTION/BACKGROUND

Hypodermic syringes are widely used to deliver fluids to the body. It isknown to have hypodermic syringes applicable for manual operation.However, auto injectors, such as electronic auto injectors, have beendeveloped and are widely used to aid the administering of fluid ormedicaments to the body.

To avoid relying on users correctly performing certain tasks, it is ofincreasing interest that the auto injector automatically carries out asmuch as possible of the injection process.

However, for safety of the user, it is of continuous desire that suchauto injector prevents adverse use, securing or facilitating that themedicament is given appropriately, and that erroneous usage, or resultsof erroneous usage, e.g. incorrect dosage or transmission of infections,is prevented or reduced.

U.S. Pat. No. 5,808,203 discloses a pressure measuring device comprisinga sensor to detect the force upon at least a portion of a contactsurface of a syringe plunger during pressurization of a fluid mediumwithin the syringe. Determination of the pressure of the fluid mediumwithin the syringe is thereby enabled.

WO 2006/116997 discloses a handheld motor operated injection devicecomprising a motor for driving a piston rod operatively connected to awasher in order to inject a set dose of medicament from a cartridgecontaining the medicament. The injection device further comprises meansfor determining a reaction force generated in response to the motordriving the piston rod, the washer and a plunger in a forward axialdirection in the cartridge.

US 2002/107477 discloses a device for administering an injectableproduct in doses. The device includes means for determining amalfunction of the device, and a vibrator motor is accommodated by thecasing. The vibrator motor is triggered by the means for determining amalfunction such that it generates a vibrating alarm signal when amalfunction is determined.

SUMMARY

Despite the known solutions there is a need for an auto injector havingan improved safety feature in order to prevent or reduce the risk ofadverse use of the auto injector, or prevent or reduce the risks, suchas health risks, resulting from adverse use of the auto injector. Thepresent disclosure provides an auto injector, a system, and a methodimproving the safety of the auto injector and/or use of an autoinjector.

Accordingly, an auto injector for administering a medicament isdisclosed. The auto injector comprising: a housing, a cartridgereceiver, a drive module, a resistance sensor and a processing unit.

The cartridge receiver is configured to receive a cartridge comprising afirst stopper. The cartridge may comprise a medicament.

The drive module is coupled to move a plunger rod between a retractedplunger rod position and an extended plunger rod position. The plungerrod is configured to move the first stopper. The plunger rod may beconfigured to move the first stopper when the plunger rod is movedtowards the extended plunger rod position.

The resistance sensor is configured to provide a resistance signalindicative of resistance against movement of the plunger rod.

The processing unit is coupled to the drive module and to the resistancesensor. The processing unit is configured to: control the drive moduleto move the plunger rod towards the extended plunger rod position, e.g.from the retracted plunger rod position; determine present plunger rodposition; receive the resistance signal; and determine a cartridgeparameter based on the resistance signal and the present plunger rodposition. The processing unit may further be configured to control thedrive module to adjust the movement of the plunger rod based on thecartridge parameter.

Also disclosed is a system comprising an auto injector, such as thedisclosed auto injector, and a cartridge comprising a first stopper,wherein the cartridge is configured to be received in the cartridgereceiver.

Also disclosed is a method for controlling an auto injector, such as thedisclosed auto injector. The method comprising: receiving a cartridgecomprising a first stopper, such as the cartridge of the disclosedsystem; moving a plunger rod, such as the plunger rod of the autoinjector, towards an extended plunger rod position, e.g. towards thefirst stopper of the cartridge; determining present plunger rodposition; receiving a resistance signal indicative of resistance againstmovement of the plunger rod; and determining a cartridge parameter basedon the resistance signal and the present plunger rod position. Themethod may further comprise adjusting the movement of the plunger rodbased on the cartridge parameter.

It is an advantage of the present disclosure that it may aid indetermining characteristics of the received cartridge. It is a furtheradvantage of the disclosure that an auto injector may be operatedaccording to characteristics of the received cartridge.

For example, the disclosure provides a manner of determining orindicating that the cartridge received is a used cartridge and/or aflawed cartridge. Thus, an advantage of the disclosure may be that itincreases the safety of an auto injector, e.g. as the auto injector maybe prevented or restricted from using a not new cartridge.

Thus, it is a further advantage of the present disclosure, that patientsafety is increased, e.g. by decreasing the risk of transmittinginfections, and/or by decreasing the risk of incorrect dosage ofmedicament.

It is envisaged that any embodiments or elements as described inconnection with any one aspect may be used with any other aspects orembodiments, mutatis mutandis.

Movement of the plunger rod may be adjusted based on the determinedcartridge parameter. Adjusting the movement of the plunger rod maycomprise stopping the movement of the plunger rod. Alternatively oradditionally, adjusting the movement of the plunger rod may comprisemoving the plunger rod to the retracted plunger rod position. Forexample, the cartridge parameter may be indicative of the cartridgebeing not full and/or empty. The movement of the plunger rod may beadjusted to stop and/or to move the plunger rod to the retractedposition when the cartridge parameter is indicative of the cartridgebeing not full and/or empty.

The cartridge parameter may be indicative of the cartridge being notfull and/or empty, such as used, e.g. if the present plunger rodposition has reached a plunger rod threshold, such as a predeterminedplunger rod position between the retracted plunger rod position and theextended plunger rod position, and the resistance signal beingindicative of resistance against movement of the plunger rod below a lowresistance threshold, e.g. indicating a small force necessary to movethe plunger rod, hence indicating that the first stopper is in anadvanced position. The low resistance threshold may be between 1 N and15 N, such as between 5 N and 11 N. The low resistance threshold may be1 N, 5 N, or 10 N.

Adjusting the movement of the plunger rod may comprise adjusting themovement of the plunger rod, such as stopping the movement of theplunger rod and/or moving the plunger rod to the retracted plunger rodposition, if the cartridge parameter is indicative of the presentplunger rod position having reached a plunger rod threshold and theresistance signal being indicative of resistance against movement of theplunger rod below a low resistance threshold. The processing unit may beconfigured to control the drive module to adjust movement of the plungerrod, such as stopping the movement of the plunger rod and/or moving theplunger rod to the retracted plunger rod position, if the cartridgeparameter is indicative of the present plunger rod position havingreached a plunger rod threshold and the resistance signal beingindicative of resistance against movement of the plunger rod below a lowresistance threshold.

The cartridge parameter may be indicative of the cartridge being flawedand/or that no needle is attached and/or attached needle is blocked,e.g. if the resistance signal is indicative of resistance againstmovement of the plunger rod above a high resistance threshold, e.g.indicating a large force necessary to move the plunger rod, henceindicating that the plunger rod and/or the first stopper is somehowblocked from advancement. The high resistance threshold may be between 8N and 25 N, such as between 10 N and 20 N. The high resistance thresholdmay be 8 N, 11 N, or 15 N.

Adjusting the movement of the plunger rod may comprise adjusting themovement of the plunger rod, such as stopping the movement of theplunger rod and/or moving the plunger rod to the retracted plunger rodposition, if the cartridge parameter is indicative of the resistancesignal being indicative of resistance against movement of the plungerrod above a high resistance threshold. The processing unit may beconfigured to control the drive module to adjust movement of the plungerrod, such as stopping the movement of the plunger rod and/or moving theplunger rod to the retracted plunger rod position, if the cartridgeparameter is indicative of the resistance signal being indicative ofresistance against movement of the plunger rod above a high resistancethreshold.

Thresholds, such as the plunger rod threshold, the low resistancethreshold and/or the high resistance threshold, may be determined basedon the cartridge and/or a cartridge code feature. The cartridge maycomprise the cartridge code feature and/or the cartridge may form partof a cartridge assembly comprising the cartridge code feature. Thecartridge code feature may be indicative of the threshold, such as theplunger rod threshold, the low resistance threshold and/or the highresistance threshold.

The auto injector may comprise a code sensor configured to read thecartridge code feature. The code sensor may provide a code signalindicative of the cartridge code feature. The processing unit may becoupled to the code sensor. The processing unit may be configured toreceive the code signal. The processing unit may be configured todetermine the threshold, such as the plunger rod threshold, the lowresistance threshold and/or the high resistance threshold, based on thecode signal.

The resistance signal may be provided by a resistance sensor. Theresistance signal may be indicative of resistance against movement ofthe plunger rod, such as resistance against movement of the plunger rodin one direction, such as movement towards the extended plunger rodposition, such as in a first plunger rod direction. For example, theresistance signal may be indicative of the force necessary to move theplunger rod, e.g. towards the extended plunger rod position.

The resistance against movement of the plunger rod may be determined bymeasuring and/or determining electrical power consumed by the drivemodule, e.g. by measuring electrical resistance, electrical current,and/or electrical voltage of the drive module.

The resistance sensor may be configured to determine electrical powerconsumed by the drive module, e.g. by measuring electrical resistance,electrical current, and/or electrical voltage of the drive module. Theresistance sensor may comprise an electrical resistance sensor, anelectrical current sensor, and/or an electrical voltage sensor. Theresistance signal may be based on electrical power consumed by the drivemodule, such as on the determined electrical power consumed by the drivemodule. The drive module may comprise the resistance sensor.

The resistance sensor may be configured to measure pressure and/or forceapplied to a plunger rod front end of the plunger rod. The plunger rodfront end may be configured to engage with the first stopper of thecartridge. The resistance sensor may be configured to measure pressureand/or force between the plunger rod and the stopper. For example, theresistance sensor may comprise a pressure transducer and/or a forcetransducer on the plunger rod front end. The plunger rod may comprisethe resistance sensor.

The system may comprise a cartridge assembly. The cartridge may formpart of a cartridge assembly, e.g. the cartridge assembly, such as thecartridge assembly of the system, may comprise the cartridge.

The cartridge receiver of the auto injector may be configured to receivethe cartridge and/or cartridge assembly through a cartridge receiveropening. Thus, the cartridge and/or cartridge assembly may be insertedin the cartridge receiver through the cartridge receiver opening.

The cartridge may comprise a cartridge compartment. The cartridgecompartment may be configured to contain a medicament. The cartridgecompartment may contain a medicament.

The cartridge may comprise a cartridge outlet, e.g. at a first cartridgeend. The cartridge outlet may be configured for fluid communication withthe compartment, e.g. at the first cartridge end. The cartridge may beconfigured to expel medicament through the cartridge outlet. Thecartridge outlet may be configured to be coupled with a needle, such asa hypodermic needle, to provide the medicament to be expelled throughthe needle. The cartridge assembly may comprise the needle and/or aneedle assembly comprising the needle.

The cartridge may comprise a first stopper movable inside the cartridgecompartment, e.g. towards the cartridge outlet, e.g. in a first stopperdirection, such as towards the first cartridge end. For example,medicament may be expelled through the cartridge outlet upon movement ofthe first stopper, e.g. in the first stopper direction and/or towardsthe cartridge outlet.

The first stopper may be in an initial position, e.g. in an unusedcartridge, such as a new cartridge. The first stopper may be in a finalposition, e.g. in a used cartridge, such as an empty cartridge. Thefirst stopper may be in an advanced position between the initialposition and the final position. The first stopper may be in an advancedposition after having moved in the first stopper direction from theinitial position.

The plunger rod of the auto injector is configured to move the firststopper. The first plunger rod direction may be the same as the firststopper direction when the cartridge is received in the cartridgereceiver of the auto injector.

The cartridge may comprise a cartridge back face, e.g. at a secondcartridge end, such as opposite the cartridge outlet. The cartridge backface may comprise a cartridge back end opening. The cartridge back endopening may provide access for the plunger rod to the first stopper.

The auto injector may be an electronic auto injector. The auto injectormay comprise a battery. The housing may accommodate the battery. Thebattery may be a rechargeable battery. For example, the battery may be aLi-ion battery or a NiCd battery or a NiMH battery. The battery may beconfigured to be charged by connection of a charger.

The drive module is coupled to move, such as actuate, such as advance,the plunger rod. The drive module may comprise one or more electricalelements. The drive module may be configured to receive electrical powerfrom the battery. The drive module may be electrically connected to thebattery for receiving electrical power. The drive module may beaccommodated by the housing. The drive module may comprise a motor, suchas an electro-mechanical motor, such as a DC motor, e.g. a DC motor withor without brushes. The drive module may comprise a solenoid motor. Thedrive module may comprise a shape memory metal engine. The drive modulemay comprise an arrangement of springs configured to actuate the plungerrod. The drive module may comprise a pressurized gas configured toactuate the plunger rod.

The plunger rod may be configured to move, such as advance a firststopper, such as the first stopper of the cartridge. The movement of thefirst stopper may be to expel medicament from the cartridge compartmentthrough the cartridge outlet and/or to expel air from the cartridgecompartment through the cartridge outlet.

The plunger rod position, such as the present plunger rod position, suchas the plunger rod position at a specific moment in time, may bedetermined, e.g. by the processing unit. The present plunger rodposition may be determined based on detection from a sensor, such as anejection sensor and/or a tachometer.

The auto injector may comprise an ejection sensor, e.g. configured todetect the ejection, such as the expelling, of medicament and/or air inthe cartridge compartment. The ejection sensor may be configured todetect the position of the plunger rod and/or the position of the firststopper.

The auto injector may comprise a tachometer, e.g. a tachometer of thedrive module. The ejection sensor may comprise the tachometer. Thetachometer may be configured to count the revolutions of the drivemodule, such as a motor of the drive module, such as the revolutions ofthe drive module from a set point, such as a point wherein the positionof the plunger rod is known, such as the retracted plunger rod position,such as a fully retracted position of the plunger rod. The count ofrevolutions of the drive module may be used to determine the presentplunger rod position, i.e. the position of the plunger rod at a specificmoment in time.

The tachometer may be configured to provide a tachometer signalindicative of a count of revolutions of the drive module. The processingunit may be coupled to the tachometer. The processing unit may beconfigured to receive the tachometer signal. The processing unit may beconfigured to determine the present plunger rod position based on thetachometer signal.

The processing unit may be coupled to the ejection sensor. Theprocessing unit may receive from the ejection sensor a first ejectionsensor signal, such as the tachometer signal, indicative of the count ofrevolutions of the drive module. The processing unit may determine theposition of the plunger rod based on the first ejection sensor signal,e.g. the tachometer signal. The processing unit may receive a secondejection sensor signal, e.g. from the ejection sensor, indicative of theplunger rod being in a known position, such as in the retracted plungerrod position, such as a fully retracted position. The processing unitmay be configured to determine the position of the plunger rod based onthe first ejection sensor signal, e.g. the tachometer signal, and thesecond ejection sensor signal. The processing unit may be configured todetermine the present plunger rod position based on the tachometersignal and the retracted plunger rod position. For example, theprocessing unit may be configured to determine the present plunger rodposition based on the number of revolutions of the drive module sincethe plunger rod was in the retracted plunger rod position.

The auto injector may comprise a user interface, such as a userinterface allowing user input and/or provide a user output signal, suchas a visual output signal and/or an audible output signal to the user.

The user interface may comprise one or more input members including afirst input member and/or a second input member. The first input memberand/or the second input member may comprise a button.

The user interface may comprise one or more output members including afirst output member and/or a second output member. The first outputmember and/or the second output member may comprise a loudspeaker and/ora visual display and/or an LED and/or a plurality of LEDs.

The user interface may be coupled to the processing unit. The processingunit may be configured to output a user output signal via the userinterface, e.g. based on the cartridge parameter. The user output signalmay be based on the cartridge parameter. For example, the user outputsignal may be indicative of the cartridge parameter. Thus, for example,the auto injector may be configured to signal to the user that thereceived cartridge cannot be used and/or the auto injector may beconfigured to signal to the user why the received cartridge cannot beused.

BRIEF DESCRIPTION OF THE FIGURES

A more detailed description follows below with reference to the drawing,in which:

FIG. 1 illustrates an exemplary auto injector;

FIG. 2 illustrates an exemplary auto injector with a cartridge;

FIG. 3 schematically illustrates an exemplary cartridge;

FIG. 4 schematically illustrates an exemplary auto injector with acartridge;

FIG. 5 shows a block diagram of an exemplary auto injector;

FIG. 6 schematically illustrates an exemplary cartridge and a plungerrod;

FIG. 7 schematically illustrates an exemplary cartridge and a plungerrod;

FIG. 8 shows an exemplary graph of resistance vs. position; and

FIG. 9 shows a flow chart of an exemplary method.

DETAILED DESCRIPTION

Various embodiments are described hereinafter with reference to thefigures. Like reference numerals refer to like elements throughout. Likeelements will, thus, not be described in detail with respect to thedescription of each figure. It should also be noted that the figures areonly intended to facilitate the description of the embodiments. They arenot intended as an exhaustive description of the claimed invention or asa limitation on the scope of the claimed invention. In addition, anillustrated embodiment need not have all the aspects or advantagesshown. An aspect or an advantage described in conjunction with aparticular embodiment is not necessarily limited to that embodiment andcan be practiced in any other embodiments even if not so illustrated, orif not so explicitly described.

FIG. 1 illustrates an exemplary auto injector 4. The auto injector 4 maybe configured for administering a medicament. The auto injector 4 may bean electronic auto injector.

The auto injector 4 comprises a housing 6. The auto injector 4 comprisesa cartridge receiver 300. The cartridge receiver is configured toreceive a cartridge and/or a cartridge assembly comprising a cartridge.The cartridge may contain the medicament.

The cartridge receiver 300 has a cartridge receiver opening 301. Thecartridge receiver 300 is configured to receive the cartridge and/or thecartridge assembly through the cartridge receiver opening 301 in acartridge receiving direction 304 along a longitudinal axis L.

The auto injector 4 may comprise a user interface 1100, as illustrated.The auto injector 4 comprises a trigger member, such as the contactmember 1102. The contact member 1102 may be configured to be pressedagainst an injection site. The contact member 1102 may be movable in thecartridge receiving direction 304, relative to the housing, if pressedagainst the injection site. The contact member 1102 may be part of theuser interface 1100.

The user interface 1100 may comprise a first input member 1108 asillustrated, e.g. a button. The first input member 1108 may provide fora user input from a user. For example, the first input member 1108 maybe used for receiving a push from a user to proceed to a next step.

The user interface 1100 may comprise a first output member 1110 asillustrated, e.g. a plurality of LEDs. The first output member 1110 mayprovide for a user output to a user. The user interface 1100 maycomprise a second output member (not shown), e.g. a speaker. The secondoutput member may be configured to provide audible output to the user.For example, the first output member 1110 and/or the second outputmember may be used to indicate a step in the procedure to the userand/or to indicate an error message.

FIG. 2 illustrates an exemplary system 2. The system 2 comprises an autoinjector 4, as described in relation to FIG. 1, and an exemplarycartridge 700 received in the cartridge receiver 300. The cartridge 700is shown with a needle cover 908. The needle cover 908 extending out ofthe contact member 1102 to allow removal of the needle cover 908 fromthe cartridge 700.

FIG. 3 schematically illustrates an exemplary cartridge 700, such as acartridge 700 being configured to be received in the cartridge receiverof an auto injector, such as the auto injector described in relation toprevious figures.

The cartridge 700 comprises a cartridge compartment 702. The cartridgecompartment 702 may be configured for containing a medicament. Thecartridge 700 has a first end 718 and a second end 720. The cartridge700 comprises a cartridge outlet 714 at the first cartridge end 718. Thecartridge may be configured to expel medicament through the cartridgeoutlet 714.

The cartridge comprises a first stopper 708 movable inside the cartridgecompartment 702, e.g. in a first stopper direction 722, e.g. towards thefirst cartridge end 718. For example, the medicament may be expelledthrough the cartridge outlet 714 upon movement of the first stopper 708in the first stopper direction 722. The cartridge 700 comprises acartridge back face 716 at the second cartridge end 720. The cartridgeback face 716 comprises a cartridge back end opening for providingaccess to the first stopper 708 for a plunger rod.

As illustrated, the cartridge 700 may be a dual chamber cartridge. Thecartridge comprises a second stopper 710 movable inside the cartridgecompartment 702, e.g. in the first stopper direction 722, e.g. towardsthe first cartridge end 718. The cartridge compartment 702 comprises afirst cartridge subcompartment 704 and a second cartridge subcompartment706. The first cartridge subcompartment 704 is between the first stopper708 and the second stopper 710. The first cartridge subcompartment 704may comprise a liquid, such as sterile water or a buffer solution. Thesecond cartridge subcompartment 706 is between the second stopper 710and the cartridge outlet 714. The second cartridge subcompartment 706may comprise a medicament, such as a dry medicament, such as amedicament dried by lyophilization. The cartridge comprises a bypasssection 712 for providing fluid communication between the firstcartridge subcompartment 704 and the second cartridge subcompartment706. The bypass section 712 provides fluid communication between thefirst cartridge subcompartment 704 and the second cartridgesubcompartment 706 when the second stopper 710 is positioned in thebypass section 712.

FIG. 4 illustrates an exemplary system 2. The system 2 comprises an autoinjector 4, as described, for example, in relation to FIG. 1, and anexemplary cartridge assembly 600. The cartridge assembly 600 comprises acartridge 700 with a cartridge compartment 702, a needle assembly 900,and an optional cartridge code feature 1000. The cartridge assembly 600is received in the auto injector 4.

The cartridge assembly 600 comprises a cartridge holder 800. Thecartridge holder is configured for retention of the cartridge 700 in thecartridge receiver 300 of the auto injector 4. The cartridge holder 800comprises a cartridge retention member 808. The cartridge retentionmember engages with the cartridge receiver 300 for reception of thecartridge 700 and the cartridge assembly 600 in the cartridge receiver.

The needle assembly 900 comprises a needle 902 and a needle hub 904. Theneedle assembly 900 is attached to the cartridge 700, e.g. by the needlehub 904 having a cartridge holder coupling portion 906, e.g. a threadedcoupling portion, being in engagement with a needle assembly couplingportion 812 of the cartridge holder 800. The needle 902 extends throughthe cartridge outlet 714 of the cartridge 700. The cartridge outlet 714may be blocked by a resilient sealing being penetrated by the needle902, when the needle assembly 900 is attached to the cartridge 700.

The auto injector 4 comprises an optional code sensor 24 configured toread the cartridge code feature 1000. When the cartridge assembly 600 isinserted, as shown, the cartridge code feature 1000 is lined up with thecode sensor 24.

The auto injector 4 comprises a plunger rod 400. The plunger rod 400 isconfigured to advance a first stopper of the cartridge 700. The plungerrod 400 comprises an outer plunger rod 404 with an inner thread, and aninner plunger rod 402 with an outer thread. The thread of the innerplunger rod 402 is in engagement with the thread of the outer plungerrod 404. The outer plunger rod 404 is prevented from rotating relativeto the housing of the auto injector. The movement of the plunger rod 400comprises rotation of the inner plunger rod 402. The rotation of theinner plunger rod 402 results in translational movement of the outerplunger rod 404, due to the outer plunger rod 404 being rotationallyrestricted. The outer plunger rod 404, when moved translationally in thefirst stopper direction 722, is configured to abut the first stopper ofthe cartridge 700, and to move the first stopper in the first stopperdirection 722.

The drive module 500 is coupled to actuate the plunger rod 400. Thedrive module 500 is electrically connected to a battery for receivingelectrical power. The drive module 500 comprises a motor 502, such as anelectro-mechanical motor, such as a DC motor. The drive module 500comprises a transmission 504 for coupling the motor 502 to the innerplunger rod 402 of the plunger rod 400.

Although the example shown comprises a motor 502, which may be anelectro-mechanical motor, it will be readily understood that the autoinjector 4 may be realised having an alternative drive module, such ascomprising a solenoid motor, a shape memory metal engine, an arrangementof springs and/or a pressurized gas configured to actuate the plungerrod 400.

The auto injector 4 comprises an ejection sensor 26, such as a plungerrod position sensor. The ejection sensor 26 is configured to detect theposition of the plunger rod 400. In the illustrated example, theejection sensor 26 comprises a tachometer configured to count/detect therevolutions of the motor 502. Thus, the position of the plunger rod 400may be determined. The ejection sensor 26 may, based on the detection ofthe position of the plunger rod 400, detect the expelling of medicamentand/or air in the cartridge compartment. The position of the plunger rod400 is indicative of the position of the first stopper 708 of thecartridge 700.

FIG. 5 shows a block diagram of an exemplary auto injector 4. The autoinjector 4 comprises a plurality of sensors 22, 24, 26, 28, 30, 32, 34,a processing unit 20, a drive module 500, and a user interface 1100. Thesensors 22, 24, 26, 28, 30, 32, 34 are coupled to the processing unit20. The user interface 1100 is coupled to the processing unit 20. Theprocessing unit is coupled to the drive module 500.

The processing unit 20 receives signals from the sensors 22, 24, 26, 28,30, 32, 34 and the user interface 1100. The processing unit 20 isconfigured to control the drive module 500. The processing unit 20 maycontrol the drive module 500 based on one or more of the receivedsignals from the sensors 22, 24, 26, 28, 30, 32, 34 and the userinterface 1100.

The auto injector 4 comprises an orientation sensor 22. The orientationsensor 22 is configured to provide an orientation signal indicative ofthe orientation of a cartridge received in the auto injector 4. Forexample, the orientation sensor 22 may be configured to detect theorientation of the auto injector 4. The orientation of the cartridge maybe determined based on the orientation of the auto injector 4. Theorientation sensor 22 may be configured to detect the direction ofgravity. For example, the orientation sensor 22 may comprise anaccelerometer.

The processing unit 20 is coupled to the orientation sensor 22. Theprocessing unit 20 is configured to receive the orientation signal. Theprocessing unit 20 may determine the orientation of the cartridge basedon the orientation signal. The processing unit 20 may control the drivemodule 500 based on the orientation signal. For example, the processingunit 20 may be configured to control the drive module 500 to move theplunger rod based on the orientation signal. For example, the processingunit 20 may be configured to control the drive module 500 to move theplunger rod towards an extended plunger rod position only if thecartridge outlet is pointing upwards. Alternatively or additionally, theprocessing unit 20 may provide user output via the user interface 1100based on the orientation signal.

The auto injector 4 comprises a code sensor 24. The code sensor 24 isconfigured to read a cartridge code feature, and provide a code signalindicative of a cartridge code feature. For example, the code sensor maybe configured to read/detect a colour code.

The processing unit 20 is coupled to the code sensor 24. The processingunit 20 is configured to receive the code signal. The processing unit 20may determine the cartridge code feature of the cartridge assembly basedon the code signal. The processing unit 20 may be configured todetermine a threshold, such as a plunger rod threshold, based on thecode signal. The processing unit 20 may control the drive module 500based on the code signal. For example, the processing unit 20 may beconfigured to control the drive module 500 to move the plunger rodtowards the extended plunger rod position based on the code signal.Alternatively or additionally, the processing unit 20 may provide useroutput via the user interface 1100 based on the code signal.

The auto injector 4 comprises an ejection sensor 26, such as a plungerrod position sensor. The ejection sensor 26 is configured to detect theposition of the plunger rod of the auto injector 4, and provide anejection sensor signal indicative of the position of the plunger rod.The ejection sensor 26 may comprise a tachometer coupled to the drivemodule 500.

The processing unit 20 is coupled to the ejection sensor 26. Theprocessing unit 20 is configured to receive the ejection sensor signal.The processing unit 20 may determine the position of the plunger rodbased on the ejection sensor signal. The processing unit 20 may controlthe drive module 500 based on the ejection sensor signal. For example,the processing unit 20 may be configured to control the drive module 500to start, stop or continue movement of the plunger rod based on theejection sensor signal. For example, the processing unit 20 may beconfigured to determine a present plunger rod position based on theejection sensor signal. Alternatively or additionally, the processingunit 20 may provide user output via the user interface 1100 based on theejection sensor signal.

The auto injector 4 comprises a cartridge sensor 28. The cartridgesensor 28 is configured to detect reception of a cartridge assembly inthe auto injector 4. The cartridge sensor 28 provides a cartridge sensorsignal indicative of reception of a cartridge assembly.

The processing unit 20 is coupled to the cartridge sensor 28. Theprocessing unit 20 is configured to receive the cartridge sensor signal.The processing unit 20 may control the drive module 500 based on thecartridge sensor signal. For example, the processing unit 20 may beconfigured to control the drive module 500 to start movement of theplunger rod if a cartridge assembly is received, and/or only if acartridge assembly is received. Alternatively or additionally, theprocessing unit 20 may provide user output via the user interface 1100based on the cartridge sensor signal.

The code sensor 24 and the cartridge sensor 28 may be the same sensor,e.g. the code sensor 24 may be configured to detect reception of acartridge assembly and subsequently read the cartridge code feature.

The auto injector 4 comprises a needle sensor 30. The needle sensor 30is configured to detect a needle, and/or a needle assembly, and/or aneedle cover of a needle assembly, of the cartridge assembly, when thecartridge assembly is received in the auto injector 4. The needle sensor30 provides a needle signal indicative of the presence of a needle,and/or a needle assembly, and/or a needle cover of a needle assembly, ofthe cartridge assembly.

The processing unit 20 is coupled to the needle sensor 30. Theprocessing unit 20 is configured to receive the needle signal. Theprocessing unit 20 may control the drive module 500 based on the needlesignal. For example, the processing unit 20 may be configured to controlthe drive module 500 to start movement of the plunger rod only if aneedle is present, and/or only if a needle cover is not present, such asremoved. Detection of a needle cover may be indicative of a needle beingpresent. The processing unit 20 may be configured to control the drivemodule 500 to start only if a needle cover has been detected, andafterwards removed. Alternatively or additionally, the processing unit20 may provide user output via the user interface 1100 based on theneedle signal.

The auto injector 4 comprises a temperature sensor 32. The temperaturesensor 32 is configured to detect a temperature, such as a temperatureof the auto injector and/or of the cartridge and/or of the medicament.The temperature sensor 32 is configured to provide a temperature signalindicative of the temperature.

The processing unit 20 is coupled to the temperature sensor 32. Theprocessing unit 20 is configured to receive the temperature signal. Theprocessing unit 20 may be configured to determine the temperature, suchas the temperature of the auto injector and/or of the cartridge and/orof the medicament based on the temperature signal. The processing unit20 may control the drive module 500 based on the temperature signal. Forexample, the processing unit 20 may be configured to control the drivemodule 500 to move the plunger rod towards the extended plunger rodposition based on the temperature signal. Alternatively or additionally,the processing unit 20 may provide user output via the user interface1100 based on the temperature signal.

The auto injector 4 comprises a resistance sensor 34. The resistancesensor 34 is configured to detect resistance against movement of theplunger rod of the auto injector 4. The resistance sensor 34 may beconfigured to detect resistance against movement of the plunger rodbased on measurements of the drive module 500. For example, theresistance sensor 34 may be configured to detect the electrical currentof a motor of the drive module 500. The resistance sensor 34 isconfigured to provide a resistance signal indicative of resistanceagainst movement of the plunger rod.

The processing unit 20 is coupled to the resistance sensor 34. Theprocessing unit 20 is configured to receive the resistance signal. Theprocessing unit 20 may be configured to determine the resistance againstmovement of the plunger rod based on the resistance signal. Theprocessing unit 20 may control the drive module 500 based on theresistance signal. For example, the processing unit 20 may be configuredto control the drive module 500 to adjust movement of the plunger rodbased on the resistance signal. For example, the processing unit 20 maybe configured to control the drive module 500 to start, stop or continuemovement of the plunger rod based on the resistance signal.Alternatively or additionally, the processing unit 20 may provide useroutput via the user interface 1100 based on the resistance signal.

The auto injector 4 is illustrated comprising all of the above mentionedsensors. However, alternatively, the auto injector may comprise only oneor any combination of one or more of the above mentioned sensors.

The auto injector comprises a user interface 1100. The user interface1100 may comprise one or more input members, e.g. a first input member,for receiving a user input. The user interface is configured to providea user input signal indicative of the received user input.

The processing unit 20 is coupled to the user interface 1100. Theprocessing unit 20 is configured to receive the user input signal. Theprocessing unit 20 may control the drive module 500 based on the userinput signal. For example, the processing unit 20 may be configured tocontrol the drive module 500 to move the plunger rod towards theextended plunger rod position based on the user input signal.

The auto injector comprises a housing 6 accommodating the sensors 22,24, 26, 28, 30, 32, 34, processing unit 20, user interface 1100 anddrive module 500.

FIG. 6 and FIG. 7 schematically illustrate exemplary cartridgeassemblies 600 and a plunger rod 400. The cartridge assembly 600comprises a cartridge 700, such as the cartridge described in relationto FIG. 3, a cartridge holder 800, and a needle assembly 900. Forintelligibility, the auto injector comprising the plunger rod 400 is notshown.

The cartridge holder 800 comprises a cartridge retention member 808. Thecartridge retention member 808 is configured for engagement with acartridge receiver of the auto injector. The cartridge holder 800comprises a needle assembly coupling portion 812. The needle assemblycoupling portion 812 is configured for engagement with a cartridgeholder coupling portion 906 of the needle assembly 900. The needleassembly coupling portion 812 allows attachment of a needle to thecartridge 700.

The needle assembly 900 comprises a needle 902 and a needle hub 904. Theneedle assembly 900 is attached to the cartridge 700, e.g. by the needlehub 904 having a cartridge holder coupling portion 906, e.g. a threadedcoupling portion, being in engagement with a needle assembly couplingportion 812 of the cartridge holder 800. The needle 902 extends throughthe cartridge outlet 714 of the cartridge 700.

FIG. 6 schematically illustrates a situation wherein an unusedcartridge, such as a new cartridge, is received. The first stopper 708is positioned in initial position. The plunger rod 400 has moved towardsthe extended plunger rod position, such that in the present plunger rodposition a plunger rod front end 410 of the plunger rod 400 abuts thefirst stopper 708. Thus, further movement of the plunger rod 400 towardsthe extended plunger rod position, e.g. in the first plunger roddirection 422, will lead to the first stopper 708 to be moved, e.g. inthe first stopper direction 722. Movement of the plunger rod 400 towardsthe extended plunger rod position will require an increased force afterabutment of the plunger rod front end 410 to the first stopper 708, e.g.due to frictional force between the first stopper 708 and inner walls ofthe cartridge compartment 702.

FIG. 7 schematically illustrates a situation wherein a used cartridge,such as an empty cartridge, is received. The first stopper 708 ispositioned in a final position, such as an advanced position, e.g.advanced in the first stopper direction 722 compared to an initialposition. The plunger rod 400 has moved towards the extended plunger rodposition, such that in the present plunger rod position the plunger rod400 extends into the cartridge 700. Compared to the situation describedin FIG. 6, movement of the plunger rod 400 towards the extended plungerrod position does not require an increased force since the plunger rodfront end 410 does not abut the first stopper 708.

FIG. 8 shows an exemplary trace T of resistance Re against movement ofthe plunger rod dependent on the position P of the plunger rod. Theplunger rod is moved from a retracted position PR to an extendedposition PE. In the beginning of the movement, the resistance againstmovement of the plunger rod is constant Ex1, e.g. the plunger rod doesnot yet push a stopper. Afterwards, a plunger rod front end of theplunger rod abuts a first stopper of the cartridge, and the resistanceagainst movement of the plunger rod increases Ex2. The increasedresistance is caused by the resistance against movement of the firststopper, e.g. due to frictional force. The resistance may decreaseslightly after the first stopper has started moving, as illustrated.When the plunger rod approaches the extended plunger rod position PE,the resistance may increase again Ex3, e.g. due to the first stopperapproaching an end of the cartridge.

The trace T is an example of resistance against plunger rod movementwhen the cartridge received is a new and/or unused and/or normalcartridge. Determining a cartridge parameter may be based on theresistance and/or plunger rod position. Determining the cartridgeparameter may be based on one or more thresholds, such as resistancethresholds, such as a low resistance threshold Re1 and/or a highresistance threshold Re2, and/or plunger rod thresholds, such as a firstplunger rod threshold P1 and/or a second plunger rod threshold P2.

Other situations, such as situations wherein the cartridge received isapparently used and/or flawed, are exemplified by additional exemplarytraces, T2, T3, T4.

Trace T2 illustrates an exemplary situation wherein the resistanceagainst movement increases above the low resistance threshold Re1 beforethe plunger rod position has reached the first plunger rod threshold P1.Such situation may for example indicate a flawed cartridge, or thatsomething is blocking the plunger rod from moving. Following suchsituation, the plunger rod may be retracted to the retracted positionand an error message may be provided through a user interface.

Trace T3 illustrates an exemplary situation wherein the resistanceagainst movement has not increased above the low resistance thresholdRe1 before the plunger rod position has reached the second plunger rodthreshold P2. Such situation may for example indicate a cartridgewherein the first stopper is in an advanced position, e.g. a usedcartridge. Following such situation, the plunger rod may be retracted tothe retracted position and an error message may be provided through auser interface.

Trace T4 illustrates an exemplary situation wherein the resistanceagainst movement increases above a high resistance threshold Re2, e.g.after the plunger rod position has passed the first plunger rodthreshold P1. Such situation may for example indicate that the firststopper is blocked from moving, e.g. the cartridge may be flawed.Following such situation, the plunger rod may be retracted to theretracted position and an error message may be provided through a userinterface.

The thresholds, such as the low resistance threshold Re1, the highresistance threshold Re2, the first plunger rod threshold P1, and/or thesecond plunger rod threshold P2 may be individually determined for thecartridge received. For example, a processing unit may be configured todetermine one or more of the thresholds, based on a cartridge codefeature of the cartridge and/or cartridge assembly received.

FIG. 9 shows a flow chart of an exemplary method 3000 for operatingand/or controlling an auto injector, such as the auto injector asdescribed in relation to previous figures.

The method 3000 comprises receiving 3001 a cartridge comprising a firststopper; moving 3002 a plunger rod towards an extended plunger rodposition; determining 3004 present plunger rod position; receiving aresistance signal 3006; determining 3008 a cartridge parameter; andadjusting 3010 the movement of the plunger rod.

Receiving 3001 the cartridge may comprise receiving the cartridge in acartridge receiver of the auto injector.

Moving 3002 the plunger rod may comprise moving the plunger rod from aretracted plunger rod position. Moving 3002 the plunger rod may comprisemoving the plunger rod in a first plunger rod direction.

Determining 3004 present plunger rod position may be determined by aprocessing unit of the auto injector. Determining 3004 present plungerrod position may be based on detection from a sensor, such as anejection sensor, e.g. comprising a tachometer.

Receiving a resistance signal 3006 may comprise receiving the resistancesignal from a resistance sensor. The resistance signal may be indicativeof resistance against movement of the plunger rod, such as movementtowards the extended plunger rod position, such as movement in the firstplunger rod direction.

Determining 3008 a cartridge parameter may comprise determining acartridge parameter based on the resistance signal and/or the presentplunger rod position. For example, the cartridge parameter may beindicative of the cartridge being used if the present plunger rodposition has reached a plunger rod threshold and the resistance signalis indicative of resistance against movement of the plunger rod below alow resistance threshold.

Adjusting 3010 the movement of the plunger rod may be based on thecartridge parameter. For example adjusting 3010 the movement maycomprise stopping the movement of the plunger rod. Alternatively oradditionally, adjusting 3010 the movement may comprise moving theplunger rod to a retracted plunger rod position.

Adjusting 3010 the movement of the plunger rod may comprise adjustingthe movement of the plunger rod if the cartridge parameter is indicativeof the cartridge being a used cartridge, such as the cartridge parameterbeing indicative of the present plunger rod position having reached aplunger rod threshold and the resistance signal being indicative ofresistance against movement of the plunger rod below a low resistancethreshold.

Adjusting 3010 the movement of the plunger rod may comprise adjustingthe movement of the plunger rod if the cartridge parameter is indicativeof the cartridge being a flawed cartridge, such as the cartridgeparameter being indicative of the resistance signal being indicative ofresistance against movement of the plunger rod above a high resistancethreshold.

Steps of the exemplary method 3000, especially the steps of moving 3002a plunger rod; determining 3004 present plunger rod position; receivinga resistance signal 3006; determining 3008 a cartridge parameter; andadjusting 3010 the movement of the plunger rod, may be controlled by aprocessing unit, such as the processing unit of the auto injector.

Exemplary auto injectors, cartridges, systems and methods are set out inthe following items:

1. An auto-injector for administering a medicament, comprising:

-   -   a housing;    -   a cartridge receiver configured to receive a cartridge        comprising a first stopper;    -   a drive module coupled to move a plunger rod between a retracted        plunger rod position and an extended plunger rod position, the        plunger rod being configured to move the first stopper;    -   a resistance sensor configured to provide a resistance signal        indicative of resistance against movement of the plunger rod;        and    -   a processing unit coupled to the drive module and to the        resistance sensor;

the processing unit being configured to:

-   -   control the drive module to move the plunger rod towards the        extended plunger rod position;    -   determine present plunger rod position;    -   receive the resistance signal;    -   determine a cartridge parameter based on the resistance signal        and the present plunger rod position; and    -   control the drive module to adjust the movement of the plunger        rod based on the cartridge parameter.

2. Auto injector according to item 1, wherein adjusting the movement ofthe plunger rod comprises stopping the movement of the plunger rod.

3. Auto injector according to any of items 1 or 2, wherein adjusting themovement of the plunger rod comprises moving the plunger rod to theretracted plunger rod position.

4. Auto injector according to any of the preceding items, wherein theprocessing unit is configured to control the drive module to adjustmovement of the plunger rod if the cartridge parameter is indicative ofthe present plunger rod position having reached a plunger rod thresholdand the resistance signal being indicative of resistance againstmovement of the plunger rod below a low resistance threshold.

5. Auto injector according to any of the preceding items, wherein theprocessing unit is configured to control the drive module to adjustmovement of the plunger rod if the cartridge parameter is indicative ofthe resistance signal being indicative of resistance against movement ofthe plunger rod above a high resistance threshold.

6. Auto injector according to item 4 or 5 comprising a code sensorconfigured to read a cartridge code feature, the processing unit beingcoupled to the code sensor, the processing unit being configured toreceive from the code sensor a code signal indicative of the cartridgecode feature and determine the plunger rod threshold and/or the lowresistance threshold and/or the high resistance threshold based on thecode signal.

7. Auto injector according to any of the preceding items, wherein theresistance sensor is configured to determine electrical power consumedby the drive module.

8. Auto injector according to any of the preceding items, wherein theresistance sensor is configured to measure pressure and/or force appliedto a plunger rod front end of the plunger rod.

9. Auto injector according to any of the preceding items comprising atachometer configured to provide a tachometer signal indicative of acount of revolutions of the drive module, the processing unit beingcoupled to the tachometer, and the processing unit being configured toreceive the tachometer signal and determine the present plunger rodposition based on the tachometer signal.

10. Auto injector according to any of the preceding items comprising auser interface coupled to the processing unit, the processing unit beingconfigured to output a user output signal via the user interface basedon the cartridge parameter.

11. A system comprising an auto injector according to any of thepreceding items, and a cartridge comprising a first stopper, wherein thecartridge is configured to be received in the cartridge receiver.

12. Method for controlling an auto injector, the method comprising:

-   -   receiving a cartridge comprising a first stopper;    -   moving a plunger rod towards an extended plunger rod position;    -   determining present plunger rod position;    -   receiving a resistance signal indicative of resistance against        movement of the plunger rod;    -   determining a cartridge parameter based on the resistance signal        and the present plunger rod position; and    -   adjusting the movement of the plunger rod based on the cartridge        parameter.

13. Method according to item 12, wherein adjusting the movement of theplunger rod comprises stopping the movement of the plunger rod.

14. Method according to any of items 12 or 13, wherein adjusting themovement of the plunger rod comprises moving the plunger rod to aretracted plunger rod position.

15. Method according to any of items 12-14, wherein adjusting themovement of the plunger rod comprises adjusting the movement of theplunger rod if the cartridge parameter is indicative of the presentplunger rod position having reached a plunger rod threshold and theresistance signal being indicative of resistance against movement of theplunger rod below a low resistance threshold.

16. Method according to any of items 12-15, wherein adjusting themovement of the plunger rod comprises adjusting the movement of theplunger rod if the cartridge parameter is indicative of the resistancesignal being indicative of resistance against movement of the plungerrod above a high resistance threshold.

17. Method according to any of claims 12-16 comprising receiving a codesignal indicative of a cartridge code feature and determining theplunger rod threshold and/or the low resistance threshold and/or thehigh resistance threshold based on the code signal.

The invention claimed is:
 1. An auto-injector for administering a medicament, comprising: a housing; a cartridge receiver configured to receive a cartridge comprising a first stopper; a drive module coupled to move a plunger rod between a retracted plunger rod position and an extended plunger rod position, the plunger rod being configured to move the first stopper; a resistance sensor configured to provide a resistance signal indicative of resistance against movement of the plunger rod, the resistance sensor determining electrical power consumed by the drive module; and a processing unit coupled to the drive module and to the resistance sensor; wherein the processing unit is configured to: control the drive module to move the plunger rod towards the extended plunger rod position; determine present plunger rod position; receive the resistance signal; determine a cartridge parameter based on the resistance signal and the present plunger rod position; and control the drive module to adjust the movement of the plunger rod based on the cartridge parameter.
 2. The auto injector according to claim 1, wherein the processing unit is configured to control the drive module to adjust movement of the plunger rod if the cartridge parameter is indicative of the present plunger rod position having reached a plunger rod threshold and the resistance signal being indicative of resistance against movement of the plunger rod below a low resistance threshold.
 3. The auto injector according to claim 1, wherein the processing unit is configured to control the drive module to adjust movement of the plunger rod if the cartridge parameter is indicative of the resistance signal being indicative of resistance against movement of the plunger rod above a high resistance threshold.
 4. The auto injector according to claim 1, wherein adjusting the movement of the plunger rod comprises stopping the movement of the plunger rod.
 5. The auto injector according to claim 1, wherein adjusting the movement of the plunger rod comprises moving the plunger rod to the retracted plunger rod position.
 6. The auto injector according to claim 1, comprising a code sensor configured to read a cartridge code feature, the processing unit being coupled to the code sensor, the processing unit being configured to receive from the code sensor a code signal indicative of the cartridge code feature and determine the plunger rod threshold or the low resistance threshold or the high resistance threshold based on the code signal.
 7. The auto injector according to claim 1, wherein the resistance sensor is configured to measure pressure or force applied to a plunger rod front end of the plunger rod.
 8. The auto injector according to claim 1, comprising a tachometer configured to provide a tachometer signal indicative of a count of revolutions of the drive module, the processing unit being coupled to the tachometer, and the processing unit being configured to receive the tachometer signal and determine the present plunger rod position based on the tachometer signal.
 9. The auto injector according to claim 1, comprising a user interface coupled to the processing unit, the processing unit being configured to output a user output signal via the user interface based on the cartridge parameter.
 10. A method for controlling an auto injector, the method comprising: receiving a cartridge comprising a first stopper; moving a plunger rod towards an extended plunger rod position; determining present plunger rod position; receiving a resistance signal indicative of resistance against movement of the plunger rod, the resistance signal being based on electrical power consumed by the drive module; determining a cartridge parameter based on the resistance signal and the present plunger rod position; and adjusting the movement of the plunger rod based on the cartridge parameter.
 11. The method according to claim 10, further comprising adjusting the movement of the plunger rod based on the cartridge parameter if the cartridge parameter is indicative of the resistance signal being indicative of resistance against movement of the plunger rod above a high resistance threshold.
 12. The method according to claim 10, further comprising adjusting the movement of the plunger rod based on the cartridge parameter if the cartridge parameter is indicative of the present plunger rod position having reached a plunger rod threshold and the resistance signal being indicative of resistance against movement of the plunger rod below a low resistance threshold.
 13. The method according to claim 10, wherein adjusting the movement of the plunger rod comprises stopping the movement of the plunger rod.
 14. The method according to claim 10, wherein adjusting the movement of the plunger rod comprises moving the plunger rod to a retracted plunger rod position.
 15. The method according to claim 10, comprising receiving a code signal indicative of a cartridge code feature and determining the plunger rod threshold or the low resistance threshold or the high resistance threshold based on the code signal. 